The formula H2O is also the molecular formula of water. For non-molecular substances such as table salt, we represent the composition with an empirical formula. Sodium chloride is represented by NaCl, meaning that sodium and chlorine ratio in sodium chloride is 1 to 1. Again, the subscript 1 is omitted.
By Phil Myers. The annelids include earthworms, polychaete worms, and leeches. All members of the group are to some extent segmented, in other words, made up of segments that are formed by subdivisions that partially transect the body cavity.Segmentation is also called metamerism.y Phil Myers. The annelids include earthworms, polychaete worms, and leeches. All members of the group are to some extent segmented, in other words, made up of segments that are formed by subdivisions that partially transect the body cavity.
About 97% of all animals are invertebrates. Invertebrates are animals which do not have a backbone. There are nine phyla of invertebrates: Porifera, Cnidaria, Platyhelminthes, Nematoda, Rotifera, Mollusca, Annelida, Arthropoda, & Echinodermata.ll other invertebrates are protostomes in which the blastopore (first opening in embryo) in their development becomes the mouth. Echinoderms, like chordates, are deuterostomes in which the blastopore becomes the anus. Echinoderms have an endoskeleton composed of movable or fixed calcium plates called ossicles.